The investigation into the death of 58-year-old James Romansoff, of Yonkers, N.Y., is the fifth the agency has opened into Metro-North accidents since May and the second involving the death of a track worker. It is the first major incident under newly appointed Metro-North President Joseph Giulietti, who has pledged to make rider and worker safety his top priority.

"The entire Metro-North family mourns the loss of a colleague and a friend, and we offer our deepest condolences to Jim Romansoff's family," Giulietti said in a statement Monday. "Keeping our customers and employees safe is the most important job we have on the railroad. With our partners at the Federal Railroad Administration and the National Transportation Safety Board, we will re-examine our procedures and protocols to ensure we are performing our jobs with safety as the paramount concern."

A source at the railroad said Romansoff had exited the established work zone onto a section of track where trains were running. Romansoff, who worked in the railroad's power department for eight years, was killed by a Poughkeepsie-bound Hudson Line train at 12:54 a.m. on a section of the Park Avenue viaduct near 106th Street, according to the railroad.

Peter Knudson, a spokesman for the NTSB, said three investigators were traveling Monday afternoon to New York City to investigate the accident.

On Sunday night, Romansoff and his crew were working in a two-mile stretch of two adjacent tracks closed to allow them to re-electrify the section that had been shut off to enable repair to a rail switch, according to Metro-North spokeswoman Marjorie Anders.

Anders and other Metro-North officials declined to discuss whether safety protocols were in place, citing the NTSB investigation. Last week, Giulietti released a 100-day safety plan of ongoing and completed safety initiatives, including a computer system meant to protect track workers while performing maintenance.

Giulietti said further improvements would rely on the results of external reviews, including Operation Deep Dive, a 60-day investigation started in December by the Federal Railroad Administration to review Metro-North's safety protocols across the board. That report is due next week.

The new computer software system, called the enhanced employee safety system, would require rail traffic controllers to transmit a random code to a rail foreman during maintenance operations that would need to be sent back before a piece of track was reopened to rail traffic. Anders said under the system, a rail traffic controller would not be able to physically reopen a closed track until receiving the code.

The new system was created in response to NTSB's recommendations made last summer from the investigation of the death of 52-year-old Robert Ludens in May, who was struck by a train traveling 70 mph when a rookie rail traffic controller opened a section of track where Ludens was working. In response to that incident, the NTSB recommended Metro-North develop new safeguards for opening and closing tracks to address "inadequate" protection for railway workers.

"I believe it was some kind of communication problem," Milone said. "But it's really too early to determine that, and we'll have to see what the NTSB investigation discovers."

Milone said that on Monday morning Romansoff was alongside several other workers on the project to restore power to tracks. Milone said Romansoff was part of a group of about 100 workers who maintain electrified third rails that power trains.

"Unfortunately, it's a very dangerous job even on a good day, but these are the things that are inherent with the job," Milone said. "If you're not getting hit by a train, you could be electrocuted, and that's why these people are the heroes of the railroad."

Romansoff's death is the latest tragedy in a string of disasters at the railroad, including two passenger train derailments in Bridgeport and the Bronx, N.Y. and a slew of service disruptions and pervasive delays related to safety-driven track work.

The railroad's troubles began with the derailment of a train and collision with another in Bridgeport that injured 76 people, followed two weeks later by Ludens' death.

Commuters have faced ongoing delays as a result of a more rigorous track inspection regimen adopted in the wake of the Bridgeport derailment that has created a backlog of new repair projects to make the system safer.

In September, the railroad faced questions about its management when the failure of a 138,000-volt feeder cable in Mount Vernon, N.Y., disrupted electric train service for more than 13 days while a second cable was out of commission for repairs, leaving no backup power to drive trains.

In December, four people were killed in a derailment in the Bronx, N.Y. when an engineer dozed off, and a train careened into a sharp curve at 82 mph where the speed limit was 30 mph.

In late January, the entire Metro-North rail network came to a halt on a frigid night when a maintenance crew knocked out power to an auxiliary power system on the railroad's centralized signalization computer.

The Federal Railroad Administration is expected to release the results of its own review and investigation of Metro-North's safety culture and protocols by a congressional deadline next Monday.

"While we have concluded much of the investigative work related to Operation Deep Dive in order to report our findings to Congress next week, our findings will be heavily considered as we conduct our investigation into yesterday's accident and as we continue to work with Metro-North to improve its safety record going forward," said Kevin Thompson, spokesman for the FRA.

Congressional delegation members said Romansoff's death underlines the need for federal investigators to provide more information to correct safety problems at the railroad and provide necessary management oversight.

"The reason to demand answers from Metro-North and the National Transportation Safety Board is, very simply, this is the second fatal tragedy of a worker in a year and completely unacceptable," Blumenthal said. " If proper worker protection protocols are in place, there should be no such tragedies or safety incidents of this severity. Everyone who rides the rails in the Northeast has a stake in safety and reliability, including the workers who provide this essential service."

U.S. Rep. Jim Himes, D-Conn., who spent part of Monday's morning rush hour speaking with commuters at the Greenwich train station, said Giulietti and other Metro-North leaders have to restore the railroad's safety first to help rebuild public trust.

"The safety problems at Metro-North are a matter of life and death, for both passengers and employees, and the culture that allows these frequent mistakes cannot continue," Himes said. "I am eager to see Metro-North's new leadership bring the change necessary to make this essential transportation system safe and reliable."

Steven Ditmeyer, an adjunct professor of rail management at the University of Michigan, said that an advanced collision avoidance system called positive train control that uses Global Positioning Systems to avoid train crashes could also allow rail traffic controllers to pinpoint whether workers were on tracks where trains were running.

Metro-North is trying to install the system by a Dec. 31, 2015, deadline but has cited obstacles obtaining radio frequencies needed to operate the system.

"You'd know the exact location of that person so there would be confirmation when they are clear of the tracks and the computer would not allow the track to be reopened until work crews were clear of the track," Ditmeyer said.